(1) Field of the Invention
This invention relates to the chemical analysis of substances, and more particularly, to a method and apparatus for the automatic analysis of biological fluids.
(2) State of the Prior Art
In recent years, a number of automated systems have been developed for carrying out quantitative chemical analyses of fluid samples. Most of the commercially-available systems utilize liquid reagents and require analyzer equipment having intricate solution handling and transport capabilities. One widely used system, shown in U.S. Pat. No. 2,797,149, employs a continuous-flow technique in which successive samples are separated from one another by immiscible fluid segments such as gas or air bubbles. Such a system is complex and expensive, requires skilled operators, and necessitates a considerable expenditure of time and effort in repetitive cleaning operations.
Another liquid analysis system is disclosed in U.S. Pat. No. 3,788,816, in which a turntable carries a plurality of receptacles containing samples to be analyzed and a pluraltiy of tube modules which are adapted to receive preset volumes of sample and reagent. Coaxially disposed relative to the turntable is a vertically movable rotary element comprising a probe tip which serves to dispense reagents and to transfer sample to a spectrophotometer.
U.S. Pat. No. 3,883,308, to Matte, discloses liquid analysis apparatus in which a plurality of sample containers are carried on a circular support, a plurality of reagent cups are supported on a second circular support, and an aspirator is provided for transferring fluid from a sample container to a selected reagent cup. The bottom portions of the reagent cups are transparent to facilitate a photometric reading through the container.
As an alternative to liquid analysis systems, various essentially-dry analytical elements have been adopted for automated test procedures. Although these elements offer substantial storage and handling conveniences, compared to "wet-chemistry," they have enjoyed only limited success and have been used primarily for qualitative and semi-quantitative test purposes. Apparatus for use with integral analytical elements in the form of continuous webs is shown in U.S. Pat. Nos. 3,036,893 and 3,526,480. Since the reagents are contained on the web in a predetermined sequence, the versatility of this apparatus is quite limited.
Automatic slide handling apparatus is known in clinical apparatus of the "wet-chemistry" type. In one such apparatus, shown in U.S. Pat. No. 3,574,064, glass slides are fed from a single supply station onto a turntable. Slides carried on the turntable are moved past a metering station, and then through wash and incubation stations spaced around the periphery of the turntable. Slides processed by the apparatus are ejected from the turntable into a slide receiver adjacent the slide supply station. There is no provision for automatic analysis of the processed slides, and they must be manually removed from the slide receiver for examination under a laboratory microscope.
U.S. Pat. No. 3,904,372, discloses apparatus for handling chromatographic plates in which plates are removed from a supply magazine by a pick-up arm, placed in position for spotting with an aliquot of fluid, and then transferred by the pick-up arm to a liquid development tank. The pick-up arm is pivotally mounted and utilizes a vacuum means to grip and hold the plates as they are transferred from the magazine to the development tank.
Slide handling mechanisms are also known in the photographic art. Representative of these mechanisms is the U.S. Pat. to Costanza et al., No. 3,926,514. This patent discloses a slide projector having a slide supply magazine which is supported above a turntable. Slides are fed from the magazine onto the turntable which moves the slides into a position for projection; after projection, the turntable moves the slide into a receiving chamber where the slides are collected for eventual restacking in the supply magazine. The Costanza et al. slides and apparatus are not indicated as being useful for performing radiometric analysis.